Electrocoalescence of drops synchronized by size-dependent flow in microfluidic channels

Ahn, Keunho; Agresti, Jeremy J.; Chong, H.H.W.; Márquez, Manuel; Weitz, David A.

doi:10.1063/1.2218058

Cited by 280 publications

(300 citation statements)

References 14 publications

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“…The reaction that occurs between the contents of the two drops can therefore proceed through a reaction-diffusion process 91 or after mixing of the species by the flow. 100 …”

Section: B Active Fusion Approachesmentioning

confidence: 99%

Dynamics of microfluidic droplets

2010

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This critical review discusses the current understanding of the formation, transport, and merging of drops in microfluidics. We focus on the physical ingredients which determine the flow of drops in microchannels and recall classical results of fluid dynamics which help explain the observed behaviour. We begin by introducing the main physical ingredients that differentiate droplet microfluidics from single-phase microfluidics, namely the modifications to the flow and pressure fields that are introduced by the presence of interfacial tension. Then three practical aspects are studied in detail: (i) The formation of drops and the dominant interactions depending on the geometry in which they are formed.(ii) The transport of drops, namely the evaluation of drop velocity, the pressure-velocity relationships, and the flow field induced by the presence of the drop. (iii) The fusion of two drops, including different methods of bridging the liquid film between them which enables their merging.

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“…The reaction that occurs between the contents of the two drops can therefore proceed through a reaction-diffusion process 91 or after mixing of the species by the flow. 100 …”

Section: B Active Fusion Approachesmentioning

confidence: 99%

Dynamics of microfluidic droplets

2010

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“…Alternating formation of drops from two sources was recently demonstrated by finely tuning the different water and oil flowrates [9]. This approach, however, is only useful in the simplest cases where only two droplet streams are involved and the downstream conditions are constant.…”

Section: Combined Operations: Drop Fusion At Formationmentioning

confidence: 99%

An optical toolbox for total control of droplet microfluidics

2007

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The use of microfluidic drops as microreactors hinges on the active control of certain fundamental operations, such as droplet formation, transport, division and fusion. Recent work has demonstrated that local heating from a focused laser can apply a thermocapillary force on a liquid interface sufficient to block the advance of a droplet in a microchannel (Baroud et al., Phys. Rev. E. V 75, p.046302). Here, we demonstrate the usefulness of this optical approach by implementing the operations mentioned above, without the need for any special microfabrication or moving parts. Building blocks such as a droplet valve, sorter, fuser, or divider are shown, as is the combination of a valve and fuser using a single laser spot.

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“…9,13,14 Magnetic fields have also been used with success. 15 Although these methods offer significant control compared with previous efforts to implement flow-induced coalescence, electromagnetic fields place strict requirements on the composition of the fluid within the droplet, and they can damage fragile contents such as DNA and proteins.…”

Section: Introductionmentioning

confidence: 99%

Coalescence and splitting of confined droplets at microfluidic junctions

et al. 2009

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The ability to merge two droplets is an important component of droplet-based lab-on-a-chip devices, yet flow-induced coalescence is difficult to achieve due to long film drainage times compared with relatively short residence times. We examine droplet collisions at a simple microfluidic T-junction and characterize the response for a wide range of droplet sizes and speeds. We find that three primary responses occur, where coalescence occurs easily at low collision speeds, smaller droplets traveling faster slip past one another without coalescing, and larger and faster droplets can break one another into multiple segments. The critical capillary number for coalescence agrees well with previously reported scaling for isolated droplet pairs when local curvature and speed are taken into account. The critical capillary number for splitting of droplets agrees well with a previously reported stability condition for individual droplets stretching in an extensional flow. Quantifying the necessary conditions for coalescence and non-coalescence behavior should enable the informed design of lab on chip devices based on discrete liquid segments.

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Electrocoalescence of drops synchronized by size-dependent flow in microfluidic channels

Cited by 280 publications

References 14 publications

Dynamics of microfluidic droplets

Dynamics of microfluidic droplets

An optical toolbox for total control of droplet microfluidics

Coalescence and splitting of confined droplets at microfluidic junctions

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